Thermostatic down draft control for wood burning heaters



Sept. 3, 1940. I c ADAMS 2,213,235

THERMOSTATIC DOWN DRAFT CONTROL FDR WOOD BURNING HEATERS Fi le d Sept. 28, 1938 2 Sheets-Sheet 1 H. Q. 11mins H. C. ADAMS Sept. 3, 1940.

THERMOSTATIC DOWN DRAFT CONTROL FOR WOOD BURNING HEATERS Filed Sept. 28, 1938 2 Sheets-Sheet 2 2 Q4 \QL Q a [1.63. (Ida Patented Sept. 3, 1940 THERMOSTATIC DOWN DRAFT'CONTROL FOR WOOD BURNING HEATERS Holcombe C. Adams, Lynchburg, -Va., assignor to Automatic Draft and Stove Company, Incorporated, Lynchburg, Va. Application September 28, 1938, Serial No. 232,190

6 Claims. (Cl. 236-96) The object of my invention is to provide a new thermostatic down draft control for wood buming heaters; to provide a thermostat of novel construction; to provide novel means for manual as well as automatic control of the thermostat whereby a continuous draft may be maintained sumclent so that embers may be kept alive over night; and to provide an improved detail of construction as hereinafter described.

I attain these and other objects of my invention by the mechanism illustrated in the accompanying drawings, in which Figure 1 is a front elevation of my device on a wood heater;

Fig. 2 a side elevation of same;

Fig. 3 1s a top plan view of the device detached from theiwood heater, a portion being shown in horizontal section;

Fig. 4 is a vertical section through the-upper portion of the heater, a. portion of the damper being shown in section;

Fig. 5 is a detail perspective view of the thermostat, link 24 and a. portion of damper IS, the major portion of the casing 4 being broken away;

Fig. 6 is a perspective view of the damper i9 and its supporting rod [8 in an inverted .position, the most of the wall II and member l3 bein broken away; and

Fig. 7 is a bottom plan view of member 5 detached from the heater.

Referring to the accompanying drawings, l indicates a wood heater substantially elliptical in cross section and having the outlet 2, draft stack elbow 3. draft stack 4 and cover plate 5 with perforations Ill. The upper portion of the draft stack is partly encased by an envelope 6, the arcuate rear portion 1 of which is shaped to seat I s ugly on the body of the wood heater l, and is secured to it by the bolt II. The envelope 6 is provided with perforations 8 near the upper end through which the screws 80 are inserted, to engage the threaded apertures 9a of the depending flanges 9 of perforated cover plate 5.

I provide a horizontal ring l3 having an an-' nuiar depending flange l3a which is secured to the draft stack 4 by the screws l2, as shown in Fig. 3. The ring l3 has a lower flange l5 and raised flange it to engage on opposite edges of the circular damper 19,. which latter is supported by the pivot rod l8, which in turn has its ends mounted in the straps 46. The latter are spot-welded at I! or otherwise affixed to the horizontal ring 3. The damper i9 is provided with a weight element in the form of a screw v link 24 is provided which may be of any suitable size to cause a more rapid opening of the damper and also to causev it to fit snugly when closed. The damper is also provided with a small aperture 2| which provides a sufiicient down draft to prevent the flre from becoming completely extinguished even when the damper is secured in a closed position by manual control at night.

. i a As-shown in Figs. 3, 4, and 5, a U-shaped bar or clevis 22 is affixed to the damper at a position offset from center.

cotter pin 23 to which one end of the link 24 is engaged, as shown in Fig. 5. The other end of the with spaced projections 26, one set of projections being on the outside and the other set of projections being on the inside of the thermostat bar 28, the link 24 extending through an aperture 25 'in stack 4 and through the opening. 21 in shown in Figs. 3 and 5. Thermostat bar 28 is shaped in loop form at 29 and is bent at 30 to provide an offset portion 3| which is fastened to the draft stack wall 4 by suitable means such as the screws or bolts 32.

or screw 34 which is screw-threaded in the enits head end 36 in operavelope wall 6 and has tive contact with the outer surface of thermostat bar 28, as shown in Figs. 4 and 5. A nut is. welded at 35a. on the envelope wall 6, as shown in Fig. 4 to provide a substantial support for the screw-threaded rod 3|. Avspiral spring 31 is interposed between knob 33 and wall 6 partly for ornamentation and partly to exert outward pressure on the knob.

In operation, the ofiset mounting of damper l9 and pivot rod I8 plus the added weight of member 20 tends to tilt the damper to a vertical open position. The weight element 26 increases the efilciency and sensitivity of operation of the ap-;

The upturned ends of this bar are provided with apertures to receive the the thermostat bar 28, as 2 toward the stack wall 4 and pushes thelink 24 to close the damper l9 so that the edges of the damper seat on the flanges l and i4. When the temperature drops, the thermostatic member 28 of cold air into the otherwise air-tight heater body 4, the damper being automatically controlled by the thermostat.

It will be noted that a small opening I is provided in damper l9 and this opening provides a slight but suilicient amount of continuous down draft to prevent the fire from going out, even when the damperis fully closed; If it is desired to make a different adjustment of the damper from that effected by the thermostat, this may be done by manual operation "of the knob 33, which when turned in a clockwise direction will cause the threaded rod 34 to move inwardly, andas its head 36 pushes against the upper end of thermostat bar 28, it willmove that bartoward the stack 4 and operate link 24 and damper i9 to move it to a closed position. i A reverse operation will, of course, open it.

As the ring I3 is mounted within the draft stack, being fastened to it by the screws l2, it and damper i9 and associated parts are con-,- cealed. Also the straps l6 furnish a secure support for the damper pivot rod on ring l3.

Also it will be noted that the disposed projections 26 on link 24 are spacedonly slightly apart so as to secure quick operation of link 24 and damper l9 under control of thermostat bar 28,

a slight amount of play, however, being allowed.

What I claim is:

1. In combination with a heater of the type described having a draft stack, a pivotally mounteddamper for the draft stack, a weight on one side of said damper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, means aflixed to the stack for mounting one end of the thermostat, a threaded rod bearing against the free end of the thermostat, and a knob on said threaded rod for manually operating the thermostat for purposes either of adjustment or fan substituting manual closure for automatic control of the damper while maintaining the calibration of the thermostat unchanged. r

2. In combination with a heater of the type described having a draft stack, a pivotally mounted damper for the draft stack, a weight on one side of saiddamper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, one end of the thermostat being affixed to the stack, a threaded rod acting through said link to effect movement of said damper, an operating knob on said threaded rod for menually operating the thermostat for purposes either of. adjustment or for substituting manual closure of the damper for automatic control of the damper while maintaining the calibration of the thermostat unchanged, and means for concealing the aforesaid thermostat and thermostatic mechanism except the operating knob.- 3; In combination with a heaterof the type described having a draft stack, a pivotally mounted damper for tliedraft stack, a weight on one side of said damper to quickly swing the damper to open position, a link pivotally connected with the damper, a thermostat operatively connected with the link, a screw acting through said link,.a knob on said screw for manually operating the thermostat for purposes either of adjustment or for substituting manual closure for automatic control of the damper while maintaining the calibration of the thermostat unchanged, means for concealing the aforesaid thermostat and thermostatic mechanism, and a perforated cover plate affixed over the stack.

4. In combination with a wood heater of the type described having a draft stack, a ring disk mounted in said draft stack and having a downturned annular flange, said flange being aflixed to the stack, a rod pivotally mounted on said ring disk, a damper aflixed in oifset position on said rod whereby to normally swing to an open position, said damper having a small draft opening therethrough, a link operatively connected with the damper, a thermostat operatively connected with the link for automatically controlling the ,damper accordingto temperatures, means for securing one end of the thermostat to the wall of the stack, manually operated adjustable means for manually controlling the operation of the thermostat for. purposes of adjustment or for substituting manual closure for the automatic control of the damper while maintaining the calibration of the thermostat unchanged, and an envelope enclosing the aforesaid thermostat and thermostatic operating means to conceal same.

5.- The combination of a wood burning stove of the class described having a down draft inlet pipe v therefor extending spacedly along a side wall of the stove, a damper for effecting control of the flow of combustion supporting fluid through said pipe into said stove, a U-shaped thermostat hav- '.'ing fixed and movable ends arranged to be responsive to the temperature of said stove for operating said damper, means interconnecting said damper and the movable end of the thermostat,

manual means for adjustment of the damper and closing thereof while maintaining the calibration of the thermostat unchanged, a housing encompassing said thermostat whereby to render it independent of room air currents and solely responsive to the temperature conditions of the stove, and threaded means extending through said housing into engagement with the free end of said thermostat and manually adjustable to substitute the manual closure of the damper for automaticcontrol thereof.

6. The combination of a wood burning stove of the class described having a down draft inlet pipe therefor extending spacedly along a side wall of the stove, a damper for effecting control of the flow of combustion supporting fluid through said pipe into said stove, a U-shaped thermostat having'one end fixed and arranged to be responsive to the temperature of said stove for operating said damper, meanainterconnecting said damper and thermostat, said thermostat being connected to the damper to control the damper to make it responsive to stove temperature conditions, an

envelope around the,thermostat to render it free ofeifect of room air currents, means extending thermostat unchanged.

noncomnn c. spams. 

